[Alpha8484]

Evening
I have a 84 spider and have recently developed a new engine problem. The car will start up right away, idle and run fine for about 15 minutes or so.
Then suddenly I will push my foot on the accelerator and nothing will happen. Instead the car returns to a almost idle rpm and tends to have a mind of its own for 2-3 minutes. Once I feel the engine not responding to the throttle I coast over to the side of the road and sit in neutral. At this point the engine will tend to lower and increase rpm on it's own. I usually sit in the car and push on the gas pedal to try and get control back however nothing happens. After about 2 minutes of this random up and down throttling the engine will suddenly begin to respond to the gas pedal (sometimes I hear a slight pop or cough) and I will be on my way. After a few minutes of driving the same thing will happen again usually with a longer waiting period before coming back into control.
I know this isn't very much of a technical explanation, I figured car talk would have enjoy a situation like this. Does anyone have any thoughts or suggestions? Thank you

 

[bianchi2]

check the air tubes, the big black ones that run across the motor, air ducts.. they are letting air in behind the air meter flap,, there are 4 big hose type clamps, loosin them up, clean the air ducts, re-instale them,, also, you motor mount.. are they really old, if so , that also can be a problem, old mounts let the motor move around alot, causeing the air ducts to let 'false ' air into them...for motor mounts, use paul spruell motor mounts, the one's with the alumiumn caps.. , also whre are you located,.. and of corse ...PHOTOS... of the car.....or a pretty girl maybe just the car would work